This table gives selected Poisson probabilities
for values of r (conventionally called
lambda, l) from 5 through
20. (5.0 is the highest value of r for
which the chance of getting zero occurrences per unit of observation remains
at all likely; p = 0.01; it is the upper limit of our normal Poisson
Table). r = 10 is the point at which
the Normal Distribution begins to be a good approximation for the Poisson
Distribution. Probably for this reason, standard Poisson tables do not usually
go higher than r = 20.

The likeliest number of occurrences
(which is r, rounded down to the nearest whole
number) is shown in bold. It is standard,
for whole numberr, that p(r)
= p(r - 1).